Undo Send Not Working

I have the Undo Send enabled for 10 seconds. When I click Undo, it does NOT stop the message from sending. I have tried this multiple times.
I’m using Apple Mail on the latest Catalina MacOS. The Mailbutler software says I have your latest build version 2512 (12780).
Please advise.
Thanks,Roy

Hello Roy,
This is a bug that is affecting a small number of our users. The developers are working on it as we speak. You could try updating to the release from today, and see if it works better for you.
Please try reinstalling Mailbutler from this link: https://bowtie.mailbutler.io/downloads. This link will always provide the most current version of Mailbutler.
If you’re a Mojave or Catalina OS user, please do the following: go to Mail-Preferences-General-Manage Plug-ins and re-enable Mailbutler.
Please let me know if you’re still having problems.